It has been noted previously that nutrient-stressed plants generally release more soluble carbohydrate in root exudates and consequently support more mycorrhizae than plants supplied with ample nutrients. Fertilization may select strains of vesicular-arbuscular mycorrhizal (VAM) fungi that are inferior mutualists if the same characteristics that make a VAM fungus successful in roots with a lowe...

Drought is a serious environmental stress limiting growth and productivity in peanut and other crops. Nutrient uptake of peanut is reduced under drought condition, which reduces yield. The objectives of this study were to investigate nutrient uptake of peanut genotypes in response to drought and to estimate the relationship between nutrient uptake and peanut yield under different water regi...

A greenhouse experiment was conducted to determine the influence of two tropical isolates of Glomus fasciculatum and Glomus mosseae on the nutrient uptake and growth of Sesbania grandiflora. Inoculation of sterile soil with the fungi significantly improved growth and nutrient uptake by S. grandiflora, but the response of the legume was markedly better when the soil was inoculated with G. fascic...

Shrub encroachment in arid and semiarid rangelands, a worldwide phenomenon, results in a heterogeneous landscape characterized by a mosaic of nutrient-depleted barren soil bordered by nutrient-enriched shrubby areas known as ‘‘fertile islands.’’ Even though shrub encroachment is considered as a major contributor to rangeland degradation, little is known about mechanisms favoring the reversibili...

Substantial amounts of volatile organic compounds (VOCs) can be released during decomposition and these compounds can affect atmospheric chemistry, belowground processes, and the structure of microbial communities in litter and soil. However, we have a limited understanding of the types, quantities and ecological impacts of VOCs emitted from litter. Here we used a closed flow-through system and...

In South Africa during the past four decades considerable research has taken place on the nutrient requirements of sugarcane. Consequently marked changes have occurred in patterns of fertilizer use. The value of N, P and K fertil~zers for cane production is reviewed using field experimental data. Correlations established between soil and leaf analysis and crop responses to various nutrients are...

UNLABELLED Although Escherichia coli is generally considered to be predominantly a commensal of the gastrointestinal tract, a number of recent studies suggest that it is also capable of long-term survival and growth in environments outside the host. As the extraintestinal physical and chemical conditions are often different from those within the host, it is possible that distinct genetic adapta...

Theoretical arguments suggest that increased plant productivity may not only increase consumer densities but also their fluctuations. While increased consumer densities are commonly observed in fertilization experiments, experiments are seldom performed at a spatial and temporal scale where effects on population fluctuations may be observed. In this study we used a natural gradient in soil fert...